Aqueous additive systems, methods and polymeric particles

ABSTRACT

Aqueous application systems for applying additives to polymeric particles, methods of preparing aqueous emulsions which include additives having a high melting point, additives having a low melting point and an emulsifiable wax. Also disclosed are methods of applying additives to polymeric particles and to polymeric particles treated by such methods.

This is a divisional of application Ser. No. 827,042 filed on February7, 1986, which is a continuation-in-part of application Ser. No. 701,888filed on Feb. 15, 1985, now abandoned.

TECHNICAL FIELD

This invention relates to aqueous application systems for applyingadditives to polymeric particles and methods of preparing aqueousemulsions which include additives having a high melting point, additiveswhich have a low melting point and an emulsifiable wax. The inventionfurther relates to methods of applying additives to polymeric particlesand to polymeric particles treated by such methods.

BACKGROUND OF THE INVENTION

Known methods of introducing additives to polymeric particles includedry blending the materials, melting, and compounding the melted blendwith extruders and pelletizing or powdering to the desired physicalform. The additives include antioxidants, processing aids, slip agents,antiblocking agents, antistatic agents, lubricants, UV stabilizers,coupling agents and colorants.

Another method of introducing additives to polymeric particles is at theextruder hopper during end use processing. Additives such as colorants,slip agents, processing aids, blowing agents, and others are introducedto virgin polymeric particles at this stage usually in concentrate form.In many instances, difficulty is encountered in metering the exactamounts necessary to do a specific job. This is especially true foradditives such as processing aids and external lubricants which are usedat very low levels and usually cannot be added in a concentrate form.

SUMMARY OF THE INVENTION

Some polymers are presently being manufactured with technology that doesnot lend itself to melt compounding and pelletizing. Many polymers suchas high density polyethylene, linear low density polyethylene, andpolypropylene emerge from the polymerization reactor in a dry granularform, similar to a fluidized bed system. Presently, additives for thesepolymers must be introduced by melting, compounding. and thenpelletizing. This extra step increases the cost of such polymermanufacturing operations and can adversely effect the properties of suchpolymers.

Additives, such as antioxidant or thermal stabilizers, colorants or thelike can be incorporated into the aqueous emulsified or dispersedsystems of this invention. The aqueous emulsions or dispersions can beused as a spray, wipe, or dip system to coat the polymeric particlesbefore normal drying or degasing operations. Such aqueous systems may beformulated to treat polymeric particles which can then be formed intomaterials made from such particles. The resulting materials may be usedin applications such as film or packaging for food, medicine and thelike. Also, such aqueous systems may contain lubricants, mold releaseagents, antistatic agents and the like.

Polymers which emerge from the polymerization reactor in particle formwould substantially benefit from the application of such aqueousemulsions containing antioxidants and other additives by means of suchan aqueous treatment. This means of introducing additives wouldeliminate melt compounding. lower production energy requirements, andminimize heat history on the polymer particles.

DESCRIPTION OF THE INVENTION

The present invention concerns aqueous application systems for applyingadditives to polymeric particles, the system being characterized byfreedom from in situ formation of color producing complexes, said systemcomprising about 2 to about 10 percent by weight of a surfactant, about5 to about 20 percent by weight of an emulsified wax, about 0.2 to about1.0 percent by weight of a base with a pH in the range of greater than 7to equal to or less than 10.5, about 20 to about 60 percent weight of atleast one additive capable of forming color producing complexes, andabout 40 to about 60 percent by weight of water. The base may beselected from sodium tetraborate, sodium carbonate, sodium bicarbonate,calcium carbonate or magnesium carbonate. The additives may be selectedfrom tetrakis[methylene3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)-propionate]methane, octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl)-propionate,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-hydroxybenzyl)benzene,bis(2,4-di-t-butyl-phenyl) pentaerythritol diphosphite, tris(monononyl-phenyl)phosphite, 4,4' -butylidene-bis(5-methyl-2-t-butyl)phenol,tris(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate, or2,2,6,6-tetramethyl-4-piperidinyl sebacate.

The invention also concerns methods of preparing aqueous emulsions whichinclude an emulsifiable wax, a first additive component which has amelting point of 100° C. or less and a second additive component whichhas a melting point greater than 100° C., said method comprising (1)mixing, by weight, about 40 to about 65 percent water, about 12 to about20 percent of said first additive component, about 4 to about 12 percentof said second additive component, about 5 to about 20 percent of anemulsifiable wax, about 0.2 to about 1.0 percent of a base, and about 2to about 10 percent of a surfactant: (2) while agitating the mixture,raise temperature of mixture sufficient to melt all solids; (3)subsequently adding more water at a temperature of at least 85° C. in anamount to yield at least 25% solids; (4) then reheating the mixture to atemperature sufficient to maintain the solids in a molten state; (5)maintaining the heated mixture at said temperature and under pressuresufficient to prevent boiling for a period of time to ensurehomogeneity; (6) cooling said emulsion to ambient temperature.

The base preferably has a pH in the range of greater than 7 to equal toor less than 10.5 and preferably is selected from sodium tetraborate,sodium carbonate, sodium bicarbonate, calcium carbonate or magnesiumcarbonate. The first additive component is preferably selected fromoctadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate or dilaurylthiodipropionate and the second additive component is preferablyselected from tetrakis-[methylene3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)-propionate]methane,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-hydroxy-benzyl)benzeneor bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,tris(mono-nonylphenyl)phosphite or4,4'-butylidene-bis(5-methyl-2-t-butyl)phenol.

The invention also includes methods of applying additives to polymericparticles, the method comprising contacting the particles with emulsionsdisclosed herein and subsequently drying the particles to leave thesolids adhering to the particles. The invention includes polymericparticles prepared by the methods disclosed in this specification.

The present invention also involves a method for preparingmulticomponent aqueous dispersions useful for treating polymericparticles. It further provides a means of readily incoroprating highmelting components into aqueous emulsified or dispersed systems. Singlecomponent systems of high melting additives are difficult to prepare.For example, tetrakis[methylene 3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)[propionate]methane with a melting point of 110-125° C. cannot beemulsified in a single additive system. However, when used in acoemulsion with dilauryl thiodipropionate (melting point 40° C.). astable emulsion is formed. Bis(2,4-di-t-butyl-phenyl) pentaerythritoldiphosphite, a hindered phenolic phosphite with a melting range of160-175° C. cannot be emulsified in a single additive system. However,it can be used in a two- or three-component system with lower meltingadditives such as dilauryl thiodipropionate and octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl) propionate (melting point 50° C.).

Aqueous emulsions or dispersions containing potassium hydroxide orsodium hydroxide, and additives such as stabilizers for polymericparticles, may cause the formation of color complexes when certainadditives are present, such as n-octadecyl3-(3',5'-di-tert-butyl-4-hydroxyphenyl) propionate, a hindered phenolicprimary antioxidant. This color complex formation imparts undesirablecolor to the polymeric particles to which the aqueous emulsions ordispersions are applied.

However, when such aqueous emulsions or dispersions contain sodiumtetraborate, sodium carbonate, calcium carbonate, or magnesiumcarbonate, or a similar base component in the pH range >7 to >10.5,color complex formation is not observed. Such emulsions or dispersionscontaining sodium tetraborate can also contain additives such asstabilizers, for example, n-octadecyl3-(3',5-di-tert-butyl-4-hydroxyphenyl) propionate, without inpartingcolor to the polymeric particles to which the aqueous emulsions ordispersions containing the additives are applied. The addition level ofsodium tetraborate or a similar weak base to the aqueous emulsions ordispersions may vary from 0.2-1.0% by wt.

The aqueous emulsions or dispersions of theis invention contain inaddition to water, an emulsifiable wax, and the desired additives,stabilizers, colorants and the like.

The emulsifiable wax may be any wax which can be readily emulsified, forexample, emulsifiable polyolefin waxes such as oxidized polyolefin waxesor modified polyolefin waxes. Preferred oxidized polyolefin waxes may beoxidized polyethylene wax having a density of 0.939, a melt viscosity of250 cp at 125° C. and an acid number of 16; oxidized polyethylene waxhaving a density of 0.942, a melt viscosity of 900 cp at 125° C. andacid number of 15; oxidized polyethylene wax having a density of 0.955,a melt viscosity of 250 cp at 125° C. and an acid number of 16; andmaleated polypropylene wax having a density of 0.934, a melt viscosityof 400 cp at 190° C. and an acid number of 47.

The aqueous emulsions may contain an emulsifiable polyethylene waxhaving a density of 0.939, a melt viscosity of 250 cp at 125° C. and anacid number of 16. Such emulsions may also contain surfactants andemulsifiers such as commerically available Tergitol 15-S-15 [anethoxylated linear alcohol having a hydrophylic-lypophilic balance of15.4, as determined according to Griffin, W. C. Office. Dig. FederationPaint Varnish Prod. Blubs, 28, 446 (1956)], and anti-foam agents such asSWS-211 (a mixture of food grade emulsifiers, 10% by wt siliconecompounds, and water). Such emulsions may also contain potassiumhydroxide, sodium tetraborate, sodium carbonate, sodium bicarbonate,calcium carbonate or magnesium carbonate, morpholine,2-amino-2-methylpropanol, tall oil fatty acid, ethylene glycol andethoxylated stearyl alcohol [commercially available as Industrol A99],and the like.

Additives such as antioxidants, including, for example, hinderedphenols, thioesters, organophosphites, and hindered amines, may readilybe dispersed or emulsified in the aqueous emulsion system. Somepreferred materials are octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate or dilaurylthiodipropionate, tetrakis[methylene3-(3',-5'-di-tert-butyl-4'-hydroxyphenyl)propionate] methane,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-hydroxy-benzyl)benzeneor bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,tris(mono-nonylpheny)-phosphite or4,4'-butylidene-bis(5methyl-2-t-butyl)-phenol. The antioxidants may beused along or in two- or more component emulsion systems for synergisticbenefits. The various aqueous emulsions can be blended in variousproportions to provide wide latitude in additive type and concentrationlevels for various end-use requirements.

Polymeric particles include, for example, polyolefins such ascrystalline polypropylene, low density polyethylene, high densitypolyethylene and linear low density polyethylenes. Other polymericmaterials include, for example, polystyrene, polyesters, polyamides andthe like as well as copolymers such as crystalline propylene ethylenecopolymers, rubbers such as ethylene propylene rubber and the like.

The present invention provides polymeric particles which are stabilizedin a unique and efficient manner and which are free from undesirablecolor.

The invention will be further illustrated by the following examplesalthough it will be understood that these examples are included merelyfor purposes of illustration and are not intended to limit the scope ofthe invention.

EXAMPLE 1

The emulsions used in the following examples are prepared as follows:The components of the emulsion including an emulsifiable wax, a base, asurfactant, and an additive and sufficient water for a solids content ofabout 60 to 80% are mixed in a glass-lined pressure vessel. Whileagitating the mixture, the temperature is raised, under pressure toprevent boiling, to a point sufficient to melt all solids and ismaintained for a time period sufficient to ensure that the solids aremelted (usually about 30 minutes). After this heating period whilemaintaining the pressure, hot water (85°-100° C.) is added in an amountsufficient to give a final solids content of about 25-60%. The emulsionis then reheated to the previous temperature and held at a pressuresufficient to prevent boiling at this temperature for a period of timeto ensure homogeneity (usually about 10 minutes) followed by rapidcooling to ambient temperature (23° C.).

EXAMPLE 2

The following emulsion components were added to a pressure vessel: 32.3parts by wt of octadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,10.8 parts by weight of oxidized polyethylene emulsifiable wax, 0.5parts of KOH as base, 6.4 parts of surfactant (Tergitol 15-S-15) andsufficient water was added to bring the content of the mixture at thisstage to about 70% solids. The emulsion was then prepared according tothe procedure in Example 1 with the final water addition beingsufficient to make the total water content equal to 50% by wt of themixture and the solids content of the mixture to 32% by wt of octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl)-propionate in the total mixture.The resulting emulsion was applied to pellets of polypropylene having adensity of 0.902 and a melt flow rate of 9. The amount of emulsion usedwas calculated to achieve a solids level of 0.3-0.5% solids by weight onthe coated polypropylene pellets. The coated polypropylene pelletsbecame a light yellow-green in color following air drying.

EXAMPLE 3

The following emulsion components were added to a pressure vessel: 32.3parts by wt of octadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,10.8 parts by weight of oxidized polyethylene emulsifiable wax, 0.5parts of sodium tetraborate as base, 6.4 parts of surfactant (Tergitol15-S-15) and sufficient water was added to bring the content of themixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateraddition being sufficient to make the total water content equal to 50%by wt of the mixture and the solids content of the mixture to 32% by wtof octadencyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate in thetotal mixture. The resulting emulsion was applied to pellets ofpolypropylene having a density of 0.902 and a melt flow rate of 9. Theamount of emulsion used was calculated to achieve a solids level of0.3-0.5% solids by weight on the coated polypropylene pellets. Thecoated polypropylene pellets did not exhibit a color shift from theoriginal white color following air drying.

EXAMPLE 4

The following emulsion components were added to a pressure vessel: 30%by wt of an emulsifiable wax. 9% by wt of surfactant (Tergitol 15-S-15),0.75% by wt of KOH, 0.25% by wt of sodium meta-bisulfite and sufficientwater to bring the total solids content to 40%. While agitating themixture under pressure to prevent boiling, the temperature was raised toa point sufficient to melt all solids and was maintained for thirtyminutes to ensure that the solids were melted and was then rapidlycooled to ambient temperature. 25% by wt of the resultant emulsion wasadded to a one-gallon Ball-Mill, then 50% by wt of1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl)-4-hydroxybenzyl)benzene,24.9% by wt of additional water and 0.1% by wt of an antifoaming agent(SWS 211) was added and the resultant mixture was ball milled for 16hours. The final solids content of1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl)-4-hydroxy-benzyl)-benzene was50% by wt of the total mixture. The resultant emulsion/dispersion wasapplied to pellets of polypropylene having a density of 0.902 and a meltflow rate of 9. The amount of emulsion/dispersion used was calculated toachieve a solids level of 0.3-0.5% solids by weight on the coatedpolypropylene pellets. The coated polypropylene pellets became a lightpurple-violet in color following air drying.

EXAMPLE 5

An emulsion/dispersion prepared according to Example 4 and substitutingsodium tetraborate for potassium hydroxide as base was applied topellets of polypropylene having a density of 0.902 and a melt flow rateof 9. The amount of emulsion/dispersion used was calculated to achieve asolids level of 0.3-0.5% solids by weight on the coated polypropylenepellets. The coated polypropylene pellets did not exhibit a color shiftfrom the original white color following air drying.

EXAMPLE 6 (COMPARATIVE)

The following components were added to a pressure vessel: 32.3 parts bywt of tetrakis -[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methane, 10.8 parts byweight of oxidized polyethylene emulsifiable wax, 0.5 parts of KOH asbase, 6.4 parts of surfactant (Tergitol 15-S-15) and sufficient water tobring the content of the mixture at this stage to about 70% solids. Anattempt was made to prepare an emulsion according to the procedure inExample 1. The final water additional was sufficient to make the totalwater content equal to 50% by wt of the mixture and the final solidscontent of the mixture to 32% wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]-methane. The attempt toprepare the emulsion was unsuccessful due to the inability to coemulsifytetrakis[methylene-3',5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methanewith the oxidized polyethylene emulsifiable wax.

EXAMPLE 7

The following emulsion components were added to a pressure vessel: 11parts by wt of tetrakis-[methylene3-(3'-5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methane, 21 parts by wtof dilauryl thiodipropionate, 10.8 parts by weight of oxidizedpolyethylene emulsifiable wax, 0.5 parts of KOH as base, 6.4 parts ofsurfactant (Tergitol 15-S-15 ) and sufficient water to bring the contentof the mixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateraddition being sufficient to make the total water content equal to 50%by wt of the mixture and the solids content of the mixture to 32% by wtof tetrakis[methylene3-(3'-5'-di-t-butyl4'-hydroxyphenyl)propionate]methane and dilaurylthiodipropionate. A stable emulsion resulted.

EXAMPLE 8

The following emulsion components were added to a pressure vessel: 7.3parts by wt of tetrakis-[methylene3-(3'-5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methane, 21 parts by wtof dilauryl thiodipropionate, 4 parts by wt ofbis(2,4-di-t-buthylphenyl)pentaerythritol diphosphite, 10.8 parts byweight of oxidized polyethylene emulsifiable wax, 0.5 parts of KOH asbase, 6.4 parts of surfactant (Tergitol 15-S-15) and sufficient water tobring the content of the mixture at this stage to about 70% solids. Theemulsion was then prepared according to the procedure in Example 1 withthe final water addition being sufficient to make the total watercontent equal to 50% by wt of the mixture and the solids content of themixture to 32% by wt of tetrakis[methylene3-(3'-5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and dilaurylthiodipropionate and bis(2,4-di-t-butylphenyl)pentaerythritoldiphosphite in the total mixture. A stable emulsion resulted.

EXAMPLE 9

The following emulsion components were added to a pressure vessel: 32.3parts by wt of dilauryl thiodipropionate, 10.8 parts by weight ofoxidized polyethylene emulsifiable wax, 0.5 parts of KOH as base, 6.4parts of surfactant (Tergitol 15-S-15) and sufficient water to bring thecontent of the mixture at this stage to about 70% solids. The emulsionwas then prepared according to the procedure in Example 1 with the finalwater addition being sufficient to make the total water content equal to50% by wt of the mixture and the final solids content of the mixture to32% by wt of dilauryl thiodipropionate in the total mixture. A stableemulsion resulted.

EXAMPLE 10

The following emulsion components were added to a pressure vessel: 9.6parts by wt of tetrakis-[methylene3-(3'-5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methane, 16 parts by wtof dilauryl thiodipropionate, 6.4 parts by wt oftris(monononylphenyl)phosphite, 10.8 parts by weight of oxidizedpolyethylene emulsifiable wax, 0.5 parts of KOH as base, 6.4 parts ofsurfactant (Tergitol 15-S-15) and sufficient water to bring the contentof the mixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateraddition being sufficient to make the total water content equal to 50%by wt of the mixture and the solids content of the mixture to 32% by wtof tetrakis[methylene3-(3'-5'-di-t-butyl-4'-hydroxyphenyl)propionate]-methane and dilaurylthiodipropionate and tris(monononylphenyl)phosphite in the totalmixture. A stable emulsion resulted.

EXAMPLE 11

The following emulsion components were added to a pressure vessel: 8parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 10.7 parts bywt of tris-(monononylphenyl)phosphite, 8 parts by wt dilaurylthiodipropionate, 13.2 parts by weight of oxidized polyethyleneemulsifiable wax, 0.75 parts of KOH as base, and 6 parts of surfactant(Tergitol 15-S-15) and sufficient water to bring the solids content ofthe mixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateraddition being sufficient to make the total water content equal to 60%by wt of the mixture and the solids content of the mixture to 23% by wtof tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]-methane,tris(nonononylphenyl)phosphite, and dilauryl thiodipropionate in thetotal mixture. A stable emulsion resulted.

EXAMPLE 12

The following emulsion components were added to a pressure vessel: 9parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)-propionate]methane, 12 parts by wtof tris(monononylphenyl)phosphite, 9 parts by weight of oxidizedpolyethylene emulsifiable wax, 0.75 parts of KOH as base, 6 parts ofsurfactant (Tergitol 15-S-15) and sufficient water to bring the solidscontent of the mixture at this stage to about 70% solids. The emulsionwas then prepared according to the procedure in Example 1 with the finalwater addition being sufficient to make the total water content equal to60% by wt of the mixture and the solids content of the mixture to 26% bywt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane,tris(nonononylphenyl)phosphite, and dilauryl thiodipropionate in thetotal mixture. A stable emulsion resulted.

EXAMPLE 13

The following emulsion components were added to a pressure vessel: 9.6parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 12.8 parts bywt of tris(monononylphenyl)phosphite, 9.6 parts by wt dilaurylthiodipropionate, 8 parts by weight of oxidized polyethyleneemulsifiable wax, 0.75 parts of KOH as base, and 6 parts of surfactant(Tergitol 15-S-15) and sufficient water to bring the solids content ofthe mixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateradditional being sufficient to make the total water content equal to 60%by wt of the mixture and the solids content of the mixture to 27% by wtof tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]-methane,tris(nonononylphenyl)phosphite, and dilauryl thiodipropionate in thetotal mixture. A stable emulsion resulted.

EXAMPLE 14

The following emulsion components were added to a pressure vessel: 10.3parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 15.4 parts bywt of tris(monononylphenyl)phosphite, 10.3 parts by wt dilaurylthiodipropionate, 4 parts by weight of oxidized polyethyleneemulsifiable wax, 0.75 parts of KOH as base, 6 parts of surfactant(Tergitol 15-S-15) and sufficient water to bring the solids content ofthe mixture at this stage to about 70% solids. The emulsion was thenprepared according to the procedure in Example 1 with the final wateraddition being sufficient to make the total water content equal to 60%by wt of the mixture and the solids content of the mixture to 31% by wtof tetradis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane,tris(monononylphenyl)phosphite, and dilauryl thiodipropionate in thetotal mixture. A stable emulsion resulted.

EXAMPLE 15 (COMPARATIVE)

The following emulsion components were added to a pressure vessel: 8parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 18.8 parts bywt dilauryl thiodipropionate, 13.2 parts by weight of oxidizedpolyethylene emulsifiable wax, 1.5 parts of KOH as base, and 6 parts ofsurfactant (Tergitol 15-S-15) and sufficient water to bring the solidscontent of the mixture at this stage to about 70% solids. The emulsionwas then prepared according to the procedure in Example 1 with the finalwater addition being sufficient total water content equal to 69% by wtof the mixture and the solids content of the mixture 17% by wt oftetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane and dilaurylthiodipropionate in the total mixture. A poor quality emulsion resulted.

EXAMPLE 16

The following emulsion components were added to a pressure vessel: 8parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 18.8 parts bywt dilauryl thiodipropionate, 13.2 parts by weight of oxidizedpolyethylene emulsifiable wax, 0.75 parts of KOH as base, 6 parts ofsurfactant (Tergitol 15-S-15) and sufficient water to bring the solidscontent of the mixture at this stage to about 70% solids. The emulsionwas then prepared according to the procedure in Example 1 with the finalwater addition being sufficient to make the total water content equal to69% by wt of the mixture and the solids content of the mixture 17% by wtof tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenbyl)propionate]-methane and dilaurylthiodipropionate in the total mixture. A stable emulsion resulted.

EXAMPLE 17 (COMPARATIVE)

The following emulsion components were added to a pressure vessel: 30parts by wt of octadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,10 parts by weight of oxidized polyethylene emulsifiable wax, 0.2 partsof sodium tetraborate as base, 6 parts of surfactant (Tergitol 15-S-15)and sufficient water to bring the solids content of the mixture at thisstage to about 70% solids. The emulsion was then prepared according tothe procedure in Example 1 with the final water addition beingsufficient to make the total water content equal to 50% by wt of themixture and the solids content of the mixture to 32.5% by wt ofoctadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate in the totalmixture. A poor quality emulsion resulted.

EXAMPLE 18

The following emulsion components were added to a pressure vessel: 30parts by wt of octadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,10 parts by weight of oxidized polyethylene emulsifiable wax, 0.4 partsof sodium tetraborate as base, 6 parts of surfactant (Tergitol 15-S-15)and sufficient water to bring the solids content of the mixture at thisstage to about 70% solids. An aqueous emulsion was then preparedaccording to the procedure in Example 1 with the final water additionbeing sufficient to make the total water content equal to 50% by wt ofthe mixture, and the solids content of the mixture 32.5% by wt ofoctadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate in the totalmixture. A stable emulsion resulted.

EXAMPLE 19

The following emulsion components were added to a pressure vessel: 30parts by wt of octadecyl 3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate,10 parts by weight of oxidized polyethylene emulsifiable wax, 0.8 partsof sodium tetraborate as base, 6 parts of surfactant (Tergitol 15-S-15)and sufficient water to bring the solids content of the mixture at thisstage to about 70% solids. The emulsion was then prepared according tothe procedure in Example 1 with the final water addition beingsufficient to make the total water content equal to 50% by wt of themixture and the solids content of the mixture to 32.5% by wt ofoctadecyl 3-(3',5'-di-t-butyl-4-hdroxyphenyl)propionate in the totalmixture. A stable emulsion resulted.

EXAMPLE 20 (Comparative)

Polypropylene pellets having a density of 0.906 and a melt flow rate of4 were melt compounded with sufficient tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane,tris(monononylphenyl)phosphite, and dilaurly thiodipropionate to providea stabilization level of 0.15%, 0.10, and 0.25% by wt respectively tothe polypropylene. Following extrusion and pelletization, the stabilizedpolypropylene was oven aged at 150° C. to check oxidative stability. Thepolypropylene had not exhibited evidence of degradation after 49 days at150° C..

EXAMPLE 21

The following emulsion components were added to a pressure vessel: 8parts by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, 13.4 parts bywt of dilauryl thiodipropionate, 5.4 parts by wt oftris(monononylphenyl)phosphite, 13.2 parts by wt of oxidizedpolyethylene emulsifiable wax, 0.75 parts by wt of KOH as base, 6 partsby wt of surfactant (Tergitol 15-S-15) and sufficient water to bring thesolids content of the mixture at this stage to about 70% solids. Theemulsion was then prepared according to the procedure in Example 1 withthe final water addition being sufficient to make the total watercontent equal to 50% by wt of the mixture and the solids content of themixture to about 17% by wt of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, dilaurylthiodipropionate, and tris(monononylphenyl)phosphite. A stable emulsionresulted.

EXAMPLE 22

The emulsion of Example 21 was applied to polypropylene pellets having adensity of 0.906 and a melt flow rate of 4 in a manner calculated tocoat the polypropylene with 0.15%, 0.25%, and 0.10% by wt, respectively,of tetrakis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, dilaurylthiodipropionare, and tris(monononylphenyl)phosphite. The coatedpolypropylene was oven aged at 150° C. to check oxidative stability. Thepolypropylene had not exhibited evidence of degradation after 49 days at150° C. indicating that polypropylene stabilized with an aqueousemulsion of tetradis[methylene3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, dilaurylthiodipropionate, and tris(monononylphenyl)phosphite compares favorablywith polyproplphenyl)phosphite compares favorably with polypropylenestabilized with the same compounds at the same level as in Example 20.

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention.

We claim:
 1. Method of preparing aqueous emulsions which include anemulsifiable wax, a first additive components which has a melting pointof 100° C. or less and a second additive component which has a meltingpoint greater than 100° C., said method comprising(1) mixing, by weight,about 40 to about 65 percent water, about 12 to about 20 percent of saidfirst additive component, about 4 to about 12 percent of said secondadditive component, about 5 to about 20 percent of an emuldifiable wax,about 0.2 to about 1.0 percent of a base, and about 2 to about 10percent of a surfactant; (2) while agitating the mixture, raisetemperature of mixture sufficient to melt all solids; (3) subsequentlyadding more water at a temperature of at least 85° C. in an amount toyield at least 25% solids; (4) then reheating the mixture to atemperature sufficient to maintain the solids in a molten state; (5)maintaining the heated mixture at said temperature and under pressuresufficient to prevent boiling for a period of time to ensurehomogeneity; (6) cooling said emulsion to ambient temperature.
 2. Methodof claim 1 wherein said base has a pH in the range of greater than 7 toequal to or less than 10.5.
 3. Method of claim 2 wherein said base isselected from sodium tetraborate, sodium carbonate, sodium bicarbonate,calcium carbonate or magnesium carbonate.
 4. Method of claim 2 whereinsaid first additive component is selected from octadecyl3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionate or dilaurylthiodipropionate.
 5. Method of claim 4 wherein said second additivecomponent is selected from tetrakis[methylene3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)-propionate]methane,1,3,5-trimethyl-2,4,6-tris-(3,5-di-tert-butyl)-4-hydroxy-benzyl)benzeneor bis(2,4-di-t-butylphenyl) pentaerythritol diphosphite,tris(nono-monylphenyl)phosphite or4,4'-butylidene-bis(5-methyl-2-t-butyl)phenol.
 6. Aqueous emulsionprepared by the method of claim 1.